KR20030010135A - manufacturing method of a liquid crystal display - Google Patents

Abstract

PURPOSE: An LCD fabricating method is provided to prevent the permeation of etching solution into cell areas by etching substrates after joining the substrates by attaching openings of auxiliary seal patterns with an adhesive agent, thereby preventing the damage of the cell areas. CONSTITUTION: An LCD fabricating method includes the steps of preparing first and second substrates defined with a plurality of cell areas to be a single LCD panel, forming a plurality of main seal patterns(421) on the first substrate to be opened partially and positioned around the cell areas respectively, forming a plurality of auxiliary seal patterns(431) surrounding the main seal patterns and having at least one or more openings(432) for discharging air, joining the first substrate formed with the auxiliary seal patterns with the second substrate, forming an adhesive agent(451) to the openings of the auxiliary seal patterns, and etching surfaces of the substrates by putting the substrates in an etching container, wherein the adhesive agent has viscosity of 5cP to 100cP.

Description

Manufacturing method of a liquid crystal display

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly, to a process of etching a substrate in order to reduce the weight of a liquid crystal display device.

Recently, with the rapid development of the information society, there is a need for a flat panel display having excellent characteristics such as thinning, light weight, and low power consumption. Among them, a liquid crystal display having excellent color reproducibility, etc. displays are actively being developed.

In general, a liquid crystal display device is formed by arranging two substrates having electrodes formed on one side thereof so that the surfaces on which the two electrodes are formed face each other, injecting a liquid crystal material between the two substrates, and then applying voltage to the two electrodes. By moving the liquid crystal molecules by the electric field is a device that represents the image by the transmittance of light that varies accordingly.

Such a liquid crystal display includes a process of manufacturing a lower array substrate on which thin film transistors and pixel electrodes are arranged, a process of manufacturing an upper color filter substrate including a color filter and a common electrode, an arrangement of the two substrates manufactured, and a liquid crystal material It is formed by a liquid crystal cell process consisting of implantation and sealing of the film, and adhesion of the polarizing plate.

However, in general, since a liquid crystal display device forms a plurality of cells on a large area substrate at a time, a process of arranging the substrates and then cutting them into individual cells is required in the liquid crystal cell process.

Hereinafter, the liquid crystal cell manufacturing process of the liquid crystal display device will be described in more detail with reference to FIG. 1.

1 is a flowchart illustrating a general liquid crystal cell manufacturing process.

First, a lower thin film transistor substrate including a thin film transistor and an upper color filter substrate including a color filter are prepared (st1).

The thin film transistor substrate is formed by repeating the process of depositing and patterning a thin film several times. The number of masks used in patterning of thin films is representative of the number of processes. Currently, research is being actively conducted to reduce manufacturing costs by reducing the number of masks. .

The color filter substrate distinguishes each color filter and sequentially forms a black matrix, red (R), green (G), and blue (B) color filters and a common electrode to prevent light leakage occurring in portions other than the pixel region. By doing so. Color filters are formed by dyeing, printing, pigment dispersion, electrodeposition, and the like. A common method currently used for forming color filters is pigment dispersion.

Next, an alignment film for determining the initial alignment direction of the liquid crystal molecules is formed on each substrate (st2).

Formation of the alignment film consists of applying a polymer thin film and arranging the alignment film in a constant direction. In general, a polyimide-based organic material is mainly used for the alignment layer, and a rubbing method is used as a method of arranging the alignment layer. The rubbing method is to rub the alignment film in a certain direction by using a rubbing cloth, and has an advantage of easy alignment treatment, suitable for mass production, stable orientation, and easy control of the pretilt angle.

Next, a seal pattern is formed on one of the two substrates (st3), and the seal pattern forms a gap for injecting the liquid crystal and prevents leakage of the injected liquid crystal.

The seal pattern is formed by forming a thermosetting resin in a predetermined pattern, and a seal pattern forming method includes a screen printing method using a screen mask and a seal dispenser method using a dispenser. Currently, screen printing, which has a large process convenience, is mainly used. However, the screen mask is difficult to cope with defects caused by the contact between the mask and the alignment layer and the size of the substrate increases. .

Subsequently, in order to maintain a precise and uniform spacing between the upper substrate and the lower substrate of the liquid crystal display device, either one of the two substrates is dispersed (st4). The dispersion method of the spacer can be divided into a wet dispersion method in which the spacer is mixed by spraying alcohol and the like, and a dry dispersion method in which only the spacer is distributed. Since the device has a structure that is vulnerable to static electricity, antistatic scattering is widely used.

Next, two substrates of the liquid crystal display, that is, the thin film transistor substrate and the color filter substrate, are disposed, and the seal patterns are pressed and cured (st5).

Next, the two substrates are cut into respective cells and separated (st6). The cell cutting process includes a scribe process of forming a cutting line on the surface of the glass substrate using a diamond pen having a hardness higher than that of the glass substrate, and a break process of applying a force to cut the glass substrate.

Next, a liquid crystal is injected between the two substrates (st7). As the injection of the liquid crystal, a vacuum injection method using a pressure difference inside and outside the cell is mainly used. Here, when the liquid crystal is injected into the cell, bubbles may be formed inside the cell by minute air bubbles in the liquid crystal, which may cause a defect. Therefore, in order to prevent this, a defoaming process of removing bubbles by leaving the liquid crystal in vacuum for a long time is necessary.

When the injection of the liquid crystal is completed, the injection hole is sealed so that the liquid crystal does not flow out of the injection hole of the cell. In general, a thermosetting resin is applied to the inlet using a dispenser, and then cured to prevent the inlet.

The liquid crystal panel is completed by manufacturing a liquid crystal cell and attaching polarizers to the outside of the liquid crystal cell, and then connecting the driving circuits.

However, as the weight reduction of the liquid crystal panel is required recently, a process of etching the outer exposed surfaces of the upper and lower substrates is performed after bonding two substrates together (st5 in FIG. 1) to reduce the thickness of the substrate.

2 is a flowchart illustrating an etching process of such a substrate.

First, impurities that may be generated in the steps of the previous process are removed before etching the outer surface of the bonded substrate (st11).

When impurities are present on the outer surface of the substrate, etching defects such as the substrate may not be etched around the impurities may cause the surface of the etched substrate to become uneven. Accordingly, since diffuse reflection or refraction of light occurs, impurities are removed from the outer surface of the substrate by using isopropyl alcohol or deionized water, which is a cleaning solution, to prevent this.

Next, the cleaned bonded substrate is etched (st12). Generally, a glass substrate is used as a substrate for a liquid crystal display, and the glass substrate contains about 60% of silicon oxide (SiO ₂ ). Therefore, the bonded substrate is placed in an HF solution used for etching the oxide film (SiO ₂ ) to etch the substrate for a liquid crystal display device.

Next, the HF solution remaining on the surface of the substrate is washed and dried (st13, st14).

As described above, after the outer surface of the bonded substrate is etched, a process of cutting into each cell (st6 of FIG. 1) and a liquid crystal injection process (st 7 of FIG. 1) is performed.

However, when etching the outer surface of the bonded substrate in this way, the etching liquid penetrates between the two substrates may damage the seal pattern, or the pad inside the cell may be a problem.

The present invention has been made to solve the above-mentioned problems, the object of the present invention is to reduce the weight of the liquid crystal display device, to prevent the penetration of the etchant to protect the seal pattern and prevent the defect of the substrate of the liquid crystal display device It is to provide an etching method.

1 is a flow chart showing a general liquid crystal cell manufacturing process.

2 is a flowchart illustrating a processing process of a bonded substrate.

3 is a plan view showing a seal pattern according to the present invention.

4 is a view showing a glass substrate etching apparatus according to the present invention.

5 is a view showing the structure of a substrate according to an embodiment of the present invention.

6 is a view showing the penetration of the etchant after etching the substrate of FIG.

7 is a view showing the structure of a substrate according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view taken along the line VII-VII of FIG. 7. FIG.

9 is a view illustrating the penetration of the etchant after etching the substrate of FIG.

In the manufacturing method of the liquid crystal display device according to the present invention for achieving the above object is provided with a first substrate and a second substrate is defined a plurality of cell regions to be one liquid crystal panel, and then partially opened on the first substrate And form a plurality of main seal patterns each positioned around the cell area. Subsequently, an auxiliary seal pattern having a plurality of main seal patterns and having at least one opening is formed. Next, the first substrate on which the auxiliary seal pattern is formed is bonded to the second substrate, and an adhesive is formed in the opening of the auxiliary seal pattern. Next, the surface of the substrate is etched by dipping the first and second substrates having the adhesive formed into the etching vessel. Here, the adhesive has a viscosity of 5 centipoise (cP) to 100 centipoise.

In this case, the adhesive may preferably have a viscosity of 40 centipoise to 45 centipoise, and the adhesive may be made of a cyanoacrylate-based material.

In the present invention, etching the surface of the substrate may be performed using an HF solution.

As described above, in the present invention, in the etching of the surface of the substrate in order to reduce the weight of the liquid crystal display, an auxiliary seal pattern having an opening is formed around the main seal pattern defining the cell region, and the substrate is bonded to each other. By sealing the opening with an adhesive and etching the substrate, it is possible to smoothly remove the air inside the cell, and to prevent the etching solution from penetrating into the cell region. Therefore, damage to the cell region can be prevented.

Recently, in order to prevent the etching pattern from penetrating between the two substrates and damaging the seal pattern when etching the bonded substrate, a method of forming a double seal pattern has been proposed.

This is when forming a plurality of cells on the glass substrate, forming a main seal pattern in each cell, and an auxiliary seal pattern between the edge of the substrate and the main seal pattern, the auxiliary seal pattern is the main seal pattern of each cell Surrounds. Here, each main seal pattern has a liquid crystal inlet for injecting liquid crystal thereafter, and the auxiliary seal pattern prevents the main seal pattern from being damaged from the etching solution of the substrate.

On the other hand, the auxiliary seal pattern should not only prevent the penetration of the etchant, but also to facilitate the discharge of air between the bonded upper and lower substrates, the auxiliary seal pattern has an opening for discharging air in a predetermined area, such a In this case, since the etchant still penetrates into the cell through the opening, the pad portion of the electrode may be corroded and the substrate may be damaged.

Therefore, in the present invention, after forming the seal pattern in a double manner to bond the substrate, the substrate is etched by adhering the opening of the auxiliary seal pattern with an adhesive.

This seal pattern structure according to an embodiment of the present invention will be described in detail with reference to the drawings.

3 is a plan view illustrating a seal pattern of a liquid crystal cell according to an exemplary embodiment of the present invention, in which a region on the substrate is divided into six areas to form a 13.3 inch size cell on a 590 × 670 (cm × cm) glass substrate. The seal pattern for the case is shown.

As shown in FIG. 3, six cells of A, B, C, D, E, and F are formed on the substrate 110, and a main seal pattern 121 is formed in each cell. A liquid crystal injection hole 122 for injecting liquid crystal is formed in the center of the left side surface of the main seal pattern 121. An auxiliary seal pattern 131 is formed between the edge of the substrate 110 and the main seal pattern 121, and the auxiliary seal pattern 131 surrounds the main seal pattern 121 of each cell. Here, the auxiliary seal pattern 131 is for preventing the damage of the main seal pattern 121 from the etching solution.

On the other hand, the auxiliary seal pattern 131 should not only prevent the penetration of the etchant, but also facilitate the discharge of air between the bonded upper and lower substrates, and thus, the auxiliary seal pattern 131 opens the opening 132 for air discharge. Have

The first substrate having such a seal pattern is bonded to the second substrate, and the opening 132 of the auxiliary seal pattern 131 is bonded with an adhesive, and then about 20 bonded substrates are placed in an etching apparatus at once. Immerse the substrate surface.

At this time, the substrate etching apparatus 200 according to the embodiment of the present invention used is shown in Figure 4 (corresponds to st12 of Figure 2). As shown in the drawing, the container 211 is formed of a cover 212 provided above the container 211 and a bubble plate 213 provided inside the container 211. The container 211 and the lid 212 are sealed by a water sealant 215. The air supply pipe 216 for supplying nitrogen (N ₂ ) or oxygen (O ₂ ) from a gas cylinder (not shown) is connected to the left and right of the bubble plate 213.

The etching liquid supply pipe 218 for supplying the etching liquid from the compound mixing tank 217 is connected to the lower portion of the container 211.

The etching liquid used for etching the glass substrate 221 is discharged to the filter 219 through the etching liquid discharge pipe 228, and is stored in the buffer tank 222 after impurities are removed by the filter 219. The etchant stored and purified in the buffer tank 222 is supplied to the compound mixing tank 217, and DI (distilled water) and HF provided from the DI supply unit 112 and the HF supply unit 224 supplying the etchant compound. Are mixed. The concentration measuring device 225 installed in the compound mixing tank 217 measures the concentration of the mixed liquid in the mixing tank 217, and when the reference concentration is already set, the supply of DI and HF is stopped. At this time, the reference concentration is set within the range of 1 to 50%. In addition, in order to maintain the mixed liquid in the mixing tank 217 at a constant temperature, a PCW (cooling water) pipe (not shown) is installed inside the mixing tank. The etchant mixed in the mixing tank 217 is provided into the container by the pump 227.

In order to measure the temperature change caused by the exothermic reaction between the substrate and the etchant in the vessel 211, a temperature measuring device 229 is installed inside the vessel 211. The substrate is etched according to this temperature change. In this way, a 1.4 mm thick substrate currently on the market can be etched down to 0.5 mm. The temperature setting is determined by the following equation, which automatically stops etching when the final temperature is reached.

_{T t = T i + (K} r · N · Δt 2) / m,

(T _t : final temperature, T _i : initial temperature, K _r : reaction constant, N: number of substrates, Δt ₂ : thickness to be etched)

Therefore, when the substrate is etched after the opening of the auxiliary seal pattern is adhered with the adhesive as in the present invention, the etching solution does not penetrate into the auxiliary seal pattern (131 of FIG. 3), thereby preventing a defect.

In this case, the adhesive may have a high acid resistance, and may use a cyanoacrylate-based material having a viscosity of about 5 centipoise (cP) to about 100 centipoise. Here, centipoise (cP) is a unit of viscosity, and 1 cP is 10 ^-2 poise (P), and a state in which 1 gram (g) of fluid moves one centimeter between one second is called 1 P.

However, when the viscosity is low, the adhesive penetrates to the main seal pattern (121 of FIG. 3), and the etching solution may penetrate into the adhesive region due to the uncured adhesive, thereby causing a defect.

Thus, when the viscosity of the adhesive is low, that is, when the viscosity of the adhesive is 5 cP to 10 cP, the adhesive form formed in the opening of the auxiliary seal pattern is shown in FIG.

As shown in FIG. 5, the opening 332 of the auxiliary seal pattern 331 surrounding the main seal pattern 321 is sealed with the adhesive 351, in which case the adhesive 351 has a low viscosity. ) So that the flow becomes easier. Adhesive 351 may penetrate to the main seal pattern 321 in the substrate. Therefore, cell separation may not be performed properly in the cell cutting process (st6 in FIG. 1). Reference numeral 322 denotes a liquid crystal injection hole formed in the main seal pattern 321.

In addition, due to the whitening of the substrate and the uncuring of the adhesive 351, the etching liquid may penetrate to the region where the adhesive 351 is formed when the substrate is etched. This example is illustrated in FIG. 6.

On the other hand, when the adhesive is about 100 cP, since the viscosity of the adhesive is large, the adhesive does not spread well in the adhesive region. Accordingly, the workability is inferior since additionally applying the adhesive process.

Therefore, it is preferable to use the adhesive as having a viscosity of about 40 cP to 45 cP.

The structure of the substrate according to the preferred embodiment of the present invention is illustrated in FIG. 7, which corresponds to region S of FIG. 3.

As shown, a main seal pattern 421 is defined on the substrate 410 and has a liquid crystal injection hole 422 on one side, and an auxiliary seal pattern (circumference of the main seal pattern 421 is formed). 431 is formed. The auxiliary seal pattern 431 has an opening 432 for discharging the air therein, and the opening 432 is sealed with the adhesive 451. At this time, although not shown, the substrate 410 on which the seal patterns 421 and 431 are formed is bonded to another substrate.

Here, since the adhesive 451 has a viscosity of about 40 cP to about 45 cP, the spreading degree of the adhesive 451 is uniform to form a constant adhesive region in the opening 432.

In addition, a cross-sectional view taken along the line VII-VII in FIG. 7 is illustrated in FIG. 8, and as illustrated, the adhesive 451 is formed without a blank space between the two substrates 410 and 411.

Therefore, in the present invention, it is possible to prevent the etchant from penetrating into the cell region, which is shown in FIG. 9.

As shown in FIG. 9, when the substrate is etched after adhering the opening of the auxiliary seal pattern using an adhesive having a viscosity of 40 cP to 45 cP, the etchant does not penetrate into the adhesive region. Pad damage inside the cell can be prevented. In addition, since the adhesive region of the adhesive is formed uniformly, defects do not occur even in the cell cutting process.

The present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit of the present invention.

In the present invention, in etching the substrate in order to reduce the weight of the liquid crystal display device, an auxiliary seal pattern having an opening is formed around the main seal pattern defining the cell region, the substrate is bonded to each other, and then the opening of the auxiliary seal pattern is bonded with an adhesive. After etching the substrate, the etching liquid can be prevented from penetrating into the cell region. Therefore, damage to the cell region can be prevented.

Claims (4)

Providing first and second substrates having a plurality of cell regions defined as one liquid crystal panel; Forming a plurality of main seal patterns on the first substrate, the plurality of main seal patterns being partially open and respectively positioned around the cell region; Forming an auxiliary seal pattern surrounding the plurality of primary seal patterns and having at least one opening; Bonding the first substrate on which the auxiliary seal pattern is formed to the second substrate; Forming an adhesive in the opening of the auxiliary seal pattern; Etching the surface of the substrate by immersing the first and second substrates on which the adhesive is formed in an etching container; Including; The adhesive may have a viscosity of 5 centipoise (cP) to 100 centipoise. The method of claim 1, The adhesive has a viscosity of 40 centipoises to 45 centipoises. The method of claim 2, The adhesive is a method of manufacturing a liquid crystal display device made of a cyanoacrylate-based material. The method of claim 1, And etching the surface of the substrate using an HF solution.